I'm planning to remove StringRef::equals in favor of
StringRef::operator==.
- StringRef::operator==/!= outnumber StringRef::equals by a factor of
31 under llvm/ in terms of their usage.
- The elimination of StringRef::equals brings StringRef closer to
std::string_view, which has operator== but not equals.
- S == "foo" is more readable than S.equals("foo"), especially for
!Long.Expression.equals("str") vs Long.Expression != "str".
As part of the RemoveDIs project we need LLVM to insert instructions using
iterators wherever possible, so that the iterators can carry a bit of
debug-info. This commit implements some of that by updating the contents of
llvm/lib/Transforms/Utils to always use iterator-versions of instruction
constructors.
There are two general flavours of update:
* Almost all call-sites just call getIterator on an instruction
* Several make use of an existing iterator (scenarios where the code is
actually significant for debug-info)
The underlying logic is that any call to getFirstInsertionPt or similar
APIs that identify the start of a block need to have that iterator passed
directly to the insertion function, without being converted to a bare
Instruction pointer along the way.
Noteworthy changes:
* FindInsertedValue now takes an optional iterator rather than an
instruction pointer, as we need to always insert with iterators,
* I've added a few iterator-taking versions of some value-tracking and
DomTree methods -- they just unwrap the iterator. These are purely
convenience methods to avoid extra syntax in some passes.
* A few calls to getNextNode become std::next instead (to keep in the
theme of using iterators for positions),
* SeparateConstOffsetFromGEP has it's insertion-position field changed.
Noteworthy because it's not a purely localised spelling change.
All this should be NFC.
Fixes a problem where the explicit marking of various instructions as
conflicts did not propagate to their users. An example of this:
```
%getelementptr = getelementptr i8, <2 x ptr addrspace(1)> zeroinitializer, <2 x i64> <i64 888, i64 908>
%shufflevector = shufflevector <2 x ptr addrspace(1)> %getelementptr, <2 x ptr addrspace(1)> zeroinitializer, <4 x i32> <i32 0, i32 1, i32 2, i32 3>
%shufflevector1 = shufflevector <2 x ptr addrspace(1)> %getelementptr, <2 x ptr addrspace(1)> zeroinitializer, <4 x i32> <i32 0, i32 1, i32 2, i32 3>
%select = select i1 false, <4 x ptr addrspace(1)> %shufflevector1, <4 x ptr addrspace(1)> %shufflevector
```
Here the vector shuffles will get single base (gep) during the fixpoint
and therefore the select will get a known base (gep). We later mark the
shuffles as conflicts, but this does not change the base of select. This
gets caught by an assert where the select's type will differ from its
(wrong) base later on.
The solution in the MR is to move the explicit conflict marking into the
fixpoint phase.
---------
Co-authored-by: Petr Maj <pmaj@azul.com>
Previously, after the algorithm fixpointed, the state was manually
patched by emitting BDVs for EE instructions earlier, while marking some
(but not all) vector and vector<->scalar instructions as conflict. This
causes issues as not all instructions that required BDVs had them
emitted and due to after-fixpoint patching, the extra BDVs did not
propagate to their users.
This change fixes both by rewriting the logic for BDV insertion &
patching. Instead of inserting the BDV for EE earlier, it merely marks
every EE instruction as a conflict. The two phase insertion algorithm
(first insert empty instructions and patch the BDVState, then actually
connect the BDV instructions to their input bases) then ensures correct
propagation to all its users. Furthermore the shufflevector instruction
as well as all instances of IE instruction are conservatively marked as
conflicts as well, fixing the second problem.
This change does not fix the handling of constant values and vectors in
the BDV.
---------
Co-authored-by: Petr Maj <pmaj@azul.com>
The current implementation completely ignores argument attributes on
calls, discarding them completely when creating a statepoint from a call
instruction. This is problematic in some scenarios as the argument
attributes affect the ABI of the call, leading to undefined behavior if
called with the wrong ABI attributes. Note that this cannot be solved
either by just having the function declaration annotated with the right
parameter attributes as the call might be indirect, therefore requiring
them to be present on the arguments.
This PR simply copies all parameter attributes over from the original
call to the created statepoint.
Note that some argument attributes become invalid after the lowering as
they imply memory effects that no longer hold with the statepoints.
These do not need to be explicitly handled in this PR as they are
removed by the `stripNonValidDataFromBody`.
Move `AttributeMask` out of `llvm/IR/Attributes.h` to a new file
`llvm/IR/AttributeMask.h`. After doing this we can remove the
`#include <bitset>` and `#include <set>` directives from `Attributes.h`.
Since there are many headers including `Attributes.h`, but not needing
the definition of `AttributeMask`, this causes unnecessary bloating of
the translation units and slows down compilation.
This commit adds in the include directive for `llvm/IR/AttributeMask.h`
to the handful of source files that need to see the definition.
This reduces the total number of preprocessing tokens across the LLVM
source files in lib from (roughly) 1,917,509,187 to 1,902,982,273 - a
reduction of ~0.76%. This should result in a small improvement in
compilation time.
Differential Revision: https://reviews.llvm.org/D153728
Previously, RewriteStatepointsForGC had a hardcoded list of GC
strategies for which it would run, and using it with a custom strategy
required patching LLVM.
The logic for selecting the variables that are considered managed was
also hardcoded to use pointers in address space 1, rather than
delegating to GCStrategy::isGCManagedPointer.
This patch fixes both of these flaws: this pass now applies to all
functions whose GCStrategy returns true for useStatepoints, and checking
if a pointer is managed or not is also now done by the strategy.
One potentially questionable design decision in this change: the pass will
be enabled for all GC strategies that use statepoints. It seems unlikely
this would be a problem - consumers that don't use this pass probably
aren't adding it to the pass manager anyway - but if you had two different
GC strategies and only one wants this pass enabled then that'd need a new
flag in GCStrategy, which I can add if anyone thinks it's necessary.
This is an updated version of D140458, rebased to account for LLVM's
changes since D140504 (required by this patch) landed.
Reviewed By: dantrushin
Differential Revision: https://reviews.llvm.org/D141110
Introduce an option to rematerialize derived pointers immediately
before their uses instead of after every statepoint. This can be
beneficial when pointer is live across many statepoints but has
few uses.
Initial implementation is simple and rematerializes derived pointer
before every use, even if there are several uses in the same block
or rematerialization instructions can be hoisted etc.
Transformation is considered profitable if we would insert less
instructions than we would insert after every live statepoint.
Depends on D138910, D138911
Reviewed By: anna, skatkov
Differential Revision: https://reviews.llvm.org/D138912
Extract `rematerializeChain()` lambda into static function.
We'll need it in upcoming patch to RS4GC pass.
There is small interface change: now reversal of `ChainToBase` is
performed within this function, not outside.
Still this is non-functional change.
Reviewed By: skatkov
Differential Revision: https://reviews.llvm.org/D138910
This patch mechanically replaces None with std::nullopt where the
compiler would warn if None were deprecated. The intent is to reduce
the amount of manual work required in migrating from Optional to
std::optional.
This is part of an effort to migrate from llvm::Optional to
std::optional:
https://discourse.llvm.org/t/deprecating-llvm-optional-x-hasvalue-getvalue-getvalueor/63716
This switches everything to use the memory attribute proposed in
https://discourse.llvm.org/t/rfc-unify-memory-effect-attributes/65579.
The old argmemonly, inaccessiblememonly and inaccessiblemem_or_argmemonly
attributes are dropped. The readnone, readonly and writeonly attributes
are restricted to parameters only.
The old attributes are auto-upgraded both in bitcode and IR.
The bitcode upgrade is a policy requirement that has to be retained
indefinitely. The IR upgrade is mainly there so it's not necessary
to update all tests using memory attributes in this patch, which
is already large enough. We could drop that part after migrating
tests, or retain it longer term, to make it easier to import IR
from older LLVM versions.
High-level Function/CallBase APIs like doesNotAccessMemory() or
setDoesNotAccessMemory() are mapped transparently to the memory
attribute. Code that directly manipulates attributes (e.g. via
AttributeList) on the other hand needs to switch to working with
the memory attribute instead.
Differential Revision: https://reviews.llvm.org/D135780
The existing code doesn't expect dummy values (undef, poison, null-derived
constants etc) as arguments of these intrinsics. However, they can be there
in unreached code. Currently we fail trying to find base for them.
Handle these cases separately. Return null as base for them to be consistent
with the handling in the main algorithm in findBaseDefiningValue.
Differential Revision: https://reviews.llvm.org/D129561
Reviewed By: apilipenko
Finding BDV for vector value does not handle freeze instruction.
Adding its handling as it is done for scalar case.
Reviewed By: apilipenko
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D128254
This refactors RS4GC to cache results returned findBaseDefiningValue
and also gets rid of BaseDefiningValueResult by caching the
IsKnownBase flag for BDVs and bases.
Differential Revision: https://reviews.llvm.org/D125000
Don't check whether an input of BDV can be pruned if the input
is the BDV itself. BDV is present in the states map, so in case
the input is the BDV itself, we'd return false. So explicitly check this case.
Differential Revision: https://reviews.llvm.org/D123846
Add void casts to mark the variables used, next to the places where
they are used in assert or `LLVM_DEBUG()` expressions.
Differential Revision: https://reviews.llvm.org/D123117
The assertion verifying that a newly computed value matches what is
already cached used stripPointerCasts() to strip bitcasts, however the
values can be not only pointers, but also vectors of pointers. That is
problematic because stripPointerCasts() doesn't handle vectors of
pointers. This patch introduces an ad-hoc utility function to strip all
bitcasts regardless of the value type.
Reviewed By: skatkov, reames
Differential Revision: https://reviews.llvm.org/D119994
This makes the statepoint methods in IRBuilder accept a
FunctionCallee, which carries both the callee and function type.
This is used to add the elementtype attribute to the statepoint call.
RS4GC requires an additional tweak to actually preserve that attribute
-- previously the attributes on the call were completely overwritten.
Differential Revision: https://reviews.llvm.org/D118886
Finding re-materialization chain for derived pointer does not depend on
call site. To avoid this finding for each call site it can be extracted in
a separate routine.
Reviewers: reames, dantrushin
Reviewed By: reames
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D118676
PointerToBase is a mapping between potentially derived pointer to its base.
As soon as we are in SSA form if there is a base of derived pointer and it
is available at def of derived pointer, the same base will be available at any
point where derived pointer is alive.
So the mapping of derived pointer to base pointer is not a property
of a call site but the same on function level.
Reviewers: reames, yrouban
Reviewed By: reames
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D118604
This class is solely used as a lightweight and clean way to build a set of
attributes to be removed from an AttrBuilder. Previously AttrBuilder was used
both for building and removing, which introduced odd situation like creation of
Attribute with dummy value because the only relevant part was the attribute
kind.
Differential Revision: https://reviews.llvm.org/D116110
It is not necessary to explicitly check which attributes are
present, and only add those to the builder. We can simply list
all attributes that need to be stripped and remove them
unconditionally. This also allows us to use some nicer APIs that
don't require mucking about with attribute list indices.
